CN114309840A - Ultrasonic vibration assisted electric spark inverted cone micropore machining device and control method thereof - Google Patents

Abstract

The invention discloses an ultrasonic vibration-assisted electric spark reverse taper micro-hole machining device, comprising an electrode wire feeding device, a dual-excitation ultrasonic vibration transducer, a guide, an electrode and an electrical control device; the invention adopts the ultrasonic vibration-assisted electric spark. When processing the reverse taper micro-hole, by changing the amplitude A _x (t) and the amplitude A _y (t) of the two longitudinal ultrasonic vibration transducers and the phase difference between the two, the At any processing depth H(t) , the electrode end can show different motion trajectories, and the electrode end trajectory I is similar to the micro-hole cross-section, so as to realize the machining of inverted cone micro-holes of different shapes and sizes, effectively solving the traditional problem. The problem that EDM is difficult to process the inverted cone micro-holes, and the cavitation effect of ultrasonic vibration in the working fluid can also effectively improve the chip removal and deionization conditions during the machining of inverted cone micro-holes, and improve the processing efficiency and processing quality of inverted cone micro-holes .

Description

Ultrasonic vibration-assisted electric spark reverse taper micro-hole machining device and control method thereof

technical field

The invention relates to the technical field of micro-special processing, in particular to an ultrasonic vibration-assisted electric spark reverse taper micro-hole processing device.

Background technique

The fuel injector is an essential and important part of the engine, and the structure of the nozzle of the automobile fuel injector has a crucial influence on the fuel atomization performance. Traditional fuel injector nozzles mostly use straight hole structure, which is difficult to meet the national VI particle emission standards. Therefore, most of the current fuel injector nozzle nozzles use an inverted conical structure, which can effectively reduce the emission of particulate matter in the thermal engine state. It is almost impossible to change the internal morphology of the micro-hole by the traditional EDM micro-hole machining method, especially the inverted tapered structure is processed inside the micro-hole. In order to solve the existing problems of this kind, on the basis of the existing EDM micro-hole machining method, the present invention provides a new method of ultrasonic vibration-assisted EDM machining of inverted taper micro-holes. During the process, by changing the amplitudes Ax(t) and Ay(t) of the two longitudinal ultrasonic vibration transducers and the phase difference between them, the electrode end can be made at any machining depth H(t). The outer track I is similar to the micro-hole section, so as to realize the processing of the reverse taper micro-hole.

SUMMARY OF THE INVENTION

The invention provides a novel ultrasonic vibration electric spark reverse taper micro-hole processing device, which aims to satisfy the processing of the reverse taper micro-hole and simultaneously improve the hole-making efficiency and the hole-making quality.

The purpose of this invention is to realize through the following technical solutions:

An ultrasonic vibration-assisted electric spark reverse taper micro-hole machining device is characterized in that it includes an electrode wire feeding device, a dual excitation ultrasonic vibration transducer, a guide, an electrode, and an electrical control device.

The dual excitation ultrasonic vibration transducer is arranged under the electrode wire feeding device, the guide is installed under the dual excitation ultrasonic vibration transducer, and the electrodes pass through the electrode wire feeding device, the dual excitation ultrasonic vibration transducer, and the guide in sequence;

The dual excitation ultrasonic vibration transducer includes a fixing frame, a connecting plate, and two longitudinal vibration ultrasonic vibration transducers; both of the two longitudinal vibration ultrasonic vibration transducers include a preload bolt, a back cover, a piezoelectric ceramic sheet, and a variable amplitude. rod; the pre-tightening bolts pass through the rear cover plate, the piezoelectric ceramic sheet and the horn in turn, and are coaxially pressed by the pre-tightening bolts. The flange plate of the longitudinal ultrasonic vibration transducer is connected and fixed;

Let the depth of the microhole be H, the machining gap be h, the diameter of the electrode be d, the diameter of the through hole of the connecting plate is D, the length of the long semi-axis of the micro-hole entrance is D _x1 , the length of the short semi-axis of the micro-hole entrance is D _y1 , and the length of the micro-hole outlet is D y1 . The length of the major semi-axis is D _x2 , and the length of the minor semi-axis at the exit of the micro-hole is D _y2 , then when the processing depth of the micro-hole is H(t), the length of the major semi-axis of the micro-hole section is x(t), and the length of the minor semi-axis is x(t). y(t) can be expressed as:

The long semi-axis length B _x (t) and the short semi-axis length By ₍ t) of the motion trajectory I of the electrode end can be expressed as:

Suppose the amplitudes of the two longitudinal ultrasonic vibration transducers are A _x (t) and A _y (t) respectively, the height of the connecting plate from the guide is H ₁ , and the height of the guide from the workpiece is H ₂ . For A _x (t), A _y (t) and B _x (t), _{By (} t) have the following relationship:

To sum up, when an ultrasonic vibration-assisted EDM reverse taper micro-hole machining device is used to process the reverse taper micro-hole, for any machining depth H(t), when the amplitude A _x ( t) and A _y (t) satisfy the following conditions:

For the trajectory II formed by the dual excitation ultrasonic vibration transducer, its trajectory equation can be expressed as:

为振幅为A_x(t)的纵振超声振动换能器工作时的初始相位角，

为振幅为A_y(t)的纵振超声振动换能器工作时的初始相位角；In the formula,

is the initial phase angle of the longitudinal ultrasonic vibration transducer with an amplitude of A _x (t),

is the initial phase angle of the longitudinal ultrasonic vibration transducer whose amplitude is A _y (t);

Therefore, it can be guaranteed that the projection equation of the microhole section at the machining depth H(t) on the xoy plane is:

It can satisfy the micro-hole depth H, the micro-hole entrance long semi-axis length D _x1 , the micro-hole entrance short semi-axis length D _y1 , the micro-hole exit long semi-axis length D _x2 , and the micro-hole exit short semi-axis length D _y2 Inverted taper Micro hole machining.

和

改变振幅A_x(t)和A_y(t)的相应合成运动方程，还可实现三角型倒锥微孔、正方形倒锥微孔等异形倒锥微孔加工。The above equation is the realization method of the elliptical inverted cone micro-hole in general. In addition, the ultrasonic vibration-assisted electric spark inverted cone micro-hole processing device provided by the present invention can adjust the two longitudinal vibration ultrasonic vibration transducers. Amplitude A _x (t) and A _y (t), and initial phase angle

and

By changing the corresponding synthetic motion equations of the amplitudes A _x (t) and A _y (t), the machining of special-shaped inverted cone micro-holes such as triangular inverted-taper micro-holes and square inverted-taper micro-holes can also be realized.

Further, the moving platform is a working moving platform in the form of ball screw drive or linear motor drive.

Further, the included angle α between the central axes of the two longitudinal ultrasonic vibration transducers is 20°-180°.

Further, through holes are provided on the connecting plate, and the matching gap between the diameter of the through holes of the connecting plate and the electrodes is 0 μm-10 μm.

Further, the guide is provided with a through hole, and the matching gap between the through hole of the guide and the electrode is 0 μm-10 μm.

Further, the operating frequencies of the two longitudinal ultrasonic vibration transducers are 15kHz-5MHz.

Further, a method for controlling an ultrasonic vibration-assisted EDM reverse taper micro-hole machining device comprises the following steps:

Step 1: The electrode wire feeding device drives the electrode to feed downward through the connecting plate through hole and the guide through hole in turn, and ensures that the electrode protruding distance from the guide through hole is less than H ₂ , and set this position as the processing origin;

Step 2: Determine the processing size of the micro-hole to be reversed, including the depth H of the micro-hole, the length of the long semi-axis of the micro-hole entrance D _x1 , the length of the short semi-axis of the micro-hole entrance D _y1 , the length of the long semi-axis of the micro-hole outlet D _x2 , and the length of the micro-hole outlet short semi-axis length D _y2 ;

Step 3. Adjust the position of the dual excitation ultrasonic vibration transducer so that the height of the through hole of the connecting plate from the guide is H ₁ , the height of the guide from the workpiece is adjusted to _{H 2} , and the total machining depth value HL is set to be slightly larger than Micropore depth H;

Step 4: The electrode wire feeding device drives the electrode to feed downward to process the reverse taper micro-hole. During the processing, the micro-hole processing depth H(t) is monitored in real time, and fed back to the electrical control device to change the two longitudinal ultrasonic vibrations. The amplitude A _x (t) and amplitude A _y (t) of the energy generator are adjusted in real time according to the equation shown in formula (4), so that the length of the semi-major axis of the micro-hole section at the machining depth H(t) is x(t) , the length of the short semi-axis of the micropore section is y(t);

Step 5. When the machining depth H(t) reaches the total machining depth, the machining of the reverse taper micro-hole is completed, the length of the long semi-axis of the reverse taper micro-hole is D _x1 , the length of the short semi-axis of the micro-hole entrance is D _y1 , and the length of the micro-hole exit is half the length. The shaft length D _x2 , the short semi-axis length D _y2 of the micro-hole outlet;

Step 6: The dual excitation ultrasonic vibration transducer stops working, and the electrode wire feeding device drives the electrode back to the processing origin, waiting for the next micro-hole processing.

The invention provides an ultrasonic vibration-assisted electric spark reverse taper micro-hole machining device, which combines the characteristics of traditional electric spark technology and ultrasonic vibration technology. The amplitude A _x (t) and amplitude A _y (t) of the detector and the phase difference between them, for any processing depth H(t), the electrode tip can present different trajectories I, and the movement of the electrode tip can be guaranteed. The track I is similar to the micro-hole section, so that the reverse taper micro-hole processing of different shapes and sizes can be realized. In addition, the cavitation effect of ultrasonic vibration can effectively improve the chip removal and deionization conditions, reduce the abnormal discharge phenomenon in micro-hole machining, and improve the hole-making efficiency and hole-making quality of EDM reverse taper micro-hole machining.

Description of drawings

Fig. 1 is the schematic diagram of the ultrasonic vibration-assisted EDM reverse taper micro-hole machining device of the present invention;

2 is a schematic diagram of a dual excitation ultrasonic vibration transducer of the present invention;

Fig. 3 is the schematic diagram of the ultrasonic vibration-assisted EDM reverse taper micro-hole machining principle of the present invention;

4 is a schematic diagram of a trajectory II formed by the dual excitation ultrasonic vibration transducer of the present invention;

FIG. 5 is a schematic diagram of the electrode end movement track I and the micro-hole cross-section of the present invention;

In the figure, 1-electrode wire feeding device, 2-dual excitation ultrasonic vibration transducer, 3-guide, 4-electrode, 21-longitudinal vibration ultrasonic vibration transducer, 22-longitudinal vibration ultrasonic vibration transducer, 23-fixing frame, 24-connecting plate, 221-preloading bolt, 222-rear cover, 223-piezoelectric ceramic sheet, 224-amplifying rod.

Detailed ways

Below in conjunction with accompanying drawing and embodiment, the present invention will be further described:

The specific operation and use steps of an ultrasonic vibration-assisted EDM reverse taper micro-hole machining device of the present invention are as follows:

An ultrasonic vibration-assisted electric spark reverse taper micro-hole processing device is characterized in that it comprises an electrode wire feeding device 1, a dual excitation ultrasonic vibration transducer 2, a guide 3, an electrode 4, and an electrical control device;

The dual excitation ultrasonic vibration transducer 2 is arranged under the electrode wire feeding device 1, the guide 3 is installed under the dual excitation ultrasonic vibration transducer 2, and the electrode 4 passes through the electrode wire feeding device 1 and the dual excitation ultrasonic vibration converter in sequence. Energy device 2, guide device 3;

The dual excitation ultrasonic vibration transducer 2 includes a longitudinal ultrasonic vibration transducer 21, a longitudinal ultrasonic vibration transducer 22, a fixing frame 23, and a connecting plate 24; the longitudinal ultrasonic vibration transducer 21 and the longitudinal ultrasonic vibration transducer The device 22 includes a preload bolt 221, a rear cover plate 222, a piezoelectric ceramic sheet 223, and a horn 224; The tightening bolt 221 is coaxially pressed, the connecting plate 24 is fixed on the front end of the longitudinal ultrasonic vibration transducer 21 and the longitudinal ultrasonic vibration transducer 22, and the fixing frame 23 is exchanged with the longitudinal ultrasonic vibration transducer 21 and the longitudinal ultrasonic vibration The flange plate of the energy device 22 is connected and fixed.

Let the depth of the microhole be H, the machining gap be h, the diameter of the electrode be d, the diameter of the through hole of the connecting plate is D, the length of the long semi-axis of the micro-hole entrance is D _x1 , the length of the short semi-axis of the micro-hole entrance is D _y1 , and the length of the micro-hole outlet is D y1 . The length of the major semi-axis is D _x2 , and the length of the minor semi-axis at the exit of the micro-hole is D _y2 , then when the processing depth of the micro-hole is H(t), the length of the major semi-axis of the micro-hole section is x(t), and the length of the minor semi-axis is x(t). y(t) can be expressed as:

The long semi-axis length B _x (t) and the short semi-axis length By ₍ t) of the motion trajectory I of the electrode end can be expressed as:

Let the amplitudes of the longitudinal ultrasonic vibration transducer 21 and the longitudinal ultrasonic vibration transducer 22 be respectively A _x (t) and A _y (t), the height of the connecting plate 24 from the guide 3 is H ₁ , and the guide 3 The height from the workpiece is H ₂ , then for A _x (t), A _y (t) and B _x (t), _{By (} t) there are the following relationships:

To sum up, when an ultrasonic vibration-assisted EDM reverse taper microhole machining device is used to process the reverse taper microhole, for any processing depth H(t), when the amplitude A _x (t) of the longitudinal ultrasonic vibration transducer 21 ) and the amplitude A _y (t) of the longitudinal ultrasonic vibration transducer 22 satisfies the following conditions:

For the trajectory II formed by the dual excitation ultrasonic vibration transducer 2, its trajectory equation can be expressed as:

为纵振超声振动换能器21工作时的初始相位角，

为纵振超声振动换能器22工作时的初始相位角；in the formula

is the initial phase angle when the longitudinal ultrasonic vibration transducer 21 works,

is the initial phase angle when the longitudinal ultrasonic vibration transducer 22 works;

Therefore, it can be guaranteed that the projection equation of the microhole section at the machining depth H(t) on the xoy plane is:

It can satisfy the micro-hole depth H, the micro-hole entrance long semi-axis length D _x1 , the micro-hole entrance short semi-axis length D _y1 , the micro-hole exit long semi-axis length D _x2 , and the micro-hole exit short semi-axis length D _y2 Inverted taper Micro hole machining.

和

改变振幅A_x(t)和A_y(t)的相应合成运动方程，还可实现三角型倒锥微孔、正方形倒锥微孔等异形倒锥微孔加工。The above equation is the realization method of the elliptical inverted cone micro-hole in general. In addition, the ultrasonic vibration-assisted electric spark inverted cone micro-hole processing device provided by the present invention can adjust the two longitudinal vibration ultrasonic vibration transducers. Amplitude A _x (t) and A _y (t), and initial phase angle

and

By changing the corresponding synthetic motion equations of the amplitudes A _x (t) and A _y (t), the machining of special-shaped inverted cone micro-holes such as triangular inverted-taper micro-holes and square inverted-taper micro-holes can also be realized.

Specific embodiment one:

Carry out the reverse taper micro-hole processing of the elliptical hole, the micro-hole depth H is 3mm, the total processing depth value H _L is 3.5mm, the micro-hole entrance long semi-axis length D _x1 is 0.18mm, and the micro-hole entrance short semi-axis length D _y1 is 0.13mm, the length D _x2 of the long semi-axis of the micro-hole outlet is 0.2 mm, the length of the short semi-axis of the micro-hole outlet D _y2 is 0.15 mm, and the diameter d of the electrode is 0.1 mm. Set the following electrical processing parameters: pulse width 0.5μs, pulse interval 0.7μs, peak current 4A, processing voltage 80V and processing capacitance 8000μF, discharge gap h is 15μm;

为0，工作频率为40kHz，纵振超声振动换能器22工作时的初始相位角

为π/2，工作频率为40kHz，后盖板222尺寸为：φ20mm×φ8mm×8mm，材料为4Cr13不锈钢，压电陶瓷片223尺寸为：φ20mm×φ8mm×4mm，数量两个，材料为PZT-8；变幅杆224长度为32mm，材料为4Cr13不锈钢，连接板24通过M6的螺栓与变幅杆224连接，连接板通孔中心距变幅杆224前端16mm；The angle α between the center axes of the longitudinal ultrasonic vibration transducer 21 and the longitudinal ultrasonic vibration transducer 22 is 90°, and the initial phase angle of the longitudinal ultrasonic vibration transducer 21 when working

is 0, the operating frequency is 40 kHz, and the initial phase angle of the longitudinal ultrasonic vibration transducer 22 when working

It is π/2, the working frequency is 40kHz, the size of the rear cover plate 222 is: φ20mm×φ8mm×8mm, the material is 4Cr13 stainless steel, the size of the piezoelectric ceramic sheet 223 is: φ20mm×φ8mm×4mm, the quantity is two, and the material is PZT- 8. The length of the horn 224 is 32mm, the material is 4Cr13 stainless steel, the connecting plate 24 is connected with the horn 224 through M6 bolts, and the center of the through hole of the connecting plate is 16mm from the front end of the horn 224;

The height H ₁ of the connecting plate from the guide 3 is set to be 0.2 mm, the height H ₂ of the guide 3 from the workpiece is 1 mm, the diameter of the through hole of the connecting plate is 0.105 mm, and the amplitude A _x (t of the longitudinal ultrasonic vibration transducer 21 is controlled. ) (μm) and the amplitude A _y (t) (μm) of the longitudinal ultrasonic vibration transducer 22 are respectively:

When using the above method to process the reverse taper micro-hole, the hole-making time is 35s, the electrode loss is 53 μm, and the taper error of the finished hole is within 3%.

Specific embodiment two:

Carry out the reverse taper micro-hole processing of ordinary round holes, the micro-hole depth H is 2mm, the total processing depth value H _L is 2.4mm, the micro-hole entrance long semi-axis length D _x1 and the micro-hole entrance short semi-axis length D _y1 are both 0.18 mm, the long semi-axis length D _x2 of the micropore outlet and the short semi-axis length D _y2 of the micropore outlet are both 0.2 mm, and the electrode diameter d is 0.15 mm. Set the following electrical processing parameters: pulse width 0.3μs, pulse interval 0.2μs, peak current 4A, processing voltage 80V and processing capacitance 6000μF, discharge gap h is 10μm;

为0，工作频率为40kHz，纵振超声振动换能器22工作时的初始相位角

为π/2，工作频率为40kHz，后盖板222尺寸为：φ20mm×φ8mm×8mm，材料为4Cr13不锈钢，压电陶瓷片223尺寸为：φ20mm×φ8mm×4mm，数量两个，材料为PZT-8；变幅杆224长度为32mm，材料为4Cr13不锈钢，连接板24通过M6的螺栓与变幅杆224连接，且连接板通孔中心距变幅杆224前端16mm。The angle α between the center axes of the longitudinal ultrasonic vibration transducer 21 and the longitudinal ultrasonic vibration transducer 22 is 90°, and the initial phase angle of the longitudinal ultrasonic vibration transducer 21 when working

is 0, the operating frequency is 40 kHz, and the initial phase angle of the longitudinal ultrasonic vibration transducer 22 when working

It is π/2, the working frequency is 40kHz, the size of the rear cover plate 222 is: φ20mm×φ8mm×8mm, the material is 4Cr13 stainless steel, the size of the piezoelectric ceramic sheet 223 is: φ20mm×φ8mm×4mm, the quantity is two, and the material is PZT- 8. The length of the horn 224 is 32mm, and the material is 4Cr13 stainless steel. The connecting plate 24 is connected to the horn 224 through M6 bolts, and the center of the through hole of the connecting plate is 16mm from the front end of the horn 224.

The height H ₁ of the connecting plate from the guide 3 is set to be 0.2 mm, the height H ₂ of the guide 3 from the workpiece is 1.2 mm, the diameter of the through hole of the connecting plate is 0.155 mm, and the amplitude A _x ( t) (μm) and the amplitude A _y (t) (μm) of the longitudinal ultrasonic vibration transducer 22 are:

When using the above method to process the reverse taper micro-hole, the hole-making time is 21s, the electrode loss is 34 μm, and the taper error of the finished hole is within 2%.

The above are the preferred embodiments of the present invention, all changes made according to the technical solutions of the present invention, when the resulting functional effects do not exceed the scope of the technical solutions of the present invention, belong to the protection scope of the present invention.

Claims (7)

1. an ultrasonic vibration auxiliary electric spark reverse taper micro-hole processing device, is characterized in that, comprises electrode wire wire feeding device, dual excitation ultrasonic vibration transducer, guider, electrode, electrical control device; The dual excitation ultrasonic vibration transducer is arranged under the electrode wire feeding device, the guide is installed under the dual excitation ultrasonic vibration transducer, and the electrodes pass through the electrode wire feeding device, the dual excitation ultrasonic vibration transducer, and the guide in sequence; The dual excitation ultrasonic vibration transducer includes a fixing frame, a connecting plate, and two longitudinal vibration ultrasonic vibration transducers; both of the two longitudinal vibration ultrasonic vibration transducers include a preload bolt, a back cover, a piezoelectric ceramic sheet, and a variable amplitude. rod; the pre-tightening bolts pass through the rear cover plate, the piezoelectric ceramic sheet and the horn in turn, and are coaxially pressed by the pre-tightening bolts. The flange plate of the longitudinal ultrasonic vibration transducer is connected and fixed; For any machining depth H(t), when the amplitudes Ax(t) and Ay(t) of the two longitudinal ultrasonic vibration transducers satisfy the following conditions:

For the trajectory II formed by the dual excitation ultrasonic vibration transducer, its trajectory equation can be expressed as:

Therefore, it can be guaranteed that the projection equation of the microhole section at the machining depth H(t) on the xoy plane is:

In the formula, H is the depth of the micropore, Dx1 is the length of the long semi-axis of the entrance of the micropore, Dy1 is the length of the short semi-axis of the entrance of the micropore, Dx2 is the length of the long semi-axis of the exit of the micropore, Dy2 is the length of the short semi-axis of the exit of the micropore, h is the machining gap, d is the electrode diameter, H1 is the height of the connecting plate from the guide, H2 is the height of the guide from the workpiece,

is the initial phase angle of the longitudinal ultrasonic vibration transducer with an amplitude of Ax(t),

is the initial phase angle of the longitudinal ultrasonic vibration transducer with an amplitude of Ay(t) during operation, x(t) is the length of the long semi-axis of the microporous section, and y(t) is the length of the short semi-axis of the microporous section; By changing the amplitudes Ax(t) and Ay(t) of the two longitudinal ultrasonic vibration transducers and the phase difference between them, the trajectory II formed by the dual excitation ultrasonic vibration transducers can exhibit different motions Therefore, at any processing depth H(t), the electrode end exhibits different motion trajectories, and the electrode end trajectory I is similar to the micro-hole cross-section, so as to realize the machining of inverted taper micro-holes of different shapes and sizes. 2 . The ultrasonic vibration-assisted EDM reverse taper micro-hole machining device according to claim 1 , wherein the motion platform is a working mobile platform driven by a ball screw or a linear motor. 3 . 3 . The ultrasonic vibration-assisted EDM reverse taper micro-hole machining device according to claim 1 , wherein the angle α between the central axes of the two longitudinal ultrasonic vibration transducers is 20°-180°. 4 . 4 . The ultrasonic vibration-assisted EDM inverted cone micro-hole processing device according to claim 1 , wherein through holes are provided on the connecting plate, and the matching gap between the diameter of the through holes of the connecting plate and the electrodes is 0 μm-10 μm. 5 . 5 . The ultrasonic vibration-assisted EDM reverse taper micro-hole machining device according to claim 1 , wherein the guide is provided with a through hole, and the matching gap between the through hole of the guide and the electrode is 0 μm-10 μm. 6 . 6 . The ultrasonic vibration-assisted EDM reverse taper micro-hole machining device according to claim 1 , wherein the working frequencies of the two longitudinal ultrasonic vibration transducers are both 15kHz-5MHz. 7 . 7. a kind of ultrasonic vibration-assisted electric spark reverse taper micro-hole machining device according to claim 1, is characterized in that, the control method comprises the following steps: Step 1. The electrode wire feeding device drives the electrode to feed downwards through the connecting plate through hole and the guide through hole in turn, and ensures that the electrode protruding distance from the guide through hole is less than H2, and this position is set as the processing origin; Step 2: Determine the processing size of the micro-hole to be reversed, including the depth H of the micro-hole, the length of the long semi-axis of the micro-hole entrance Dx1, the length of the short semi-axis of the micro-hole entrance Dy1, the length of the long semi-axis of the micro-hole outlet Dx2, and the short half-axis of the micro-hole outlet. Shaft length Dy2; Step 3: Adjust the position of the dual excitation ultrasonic vibration transducer so that the height of the through hole of the connecting plate from the guide is H1, the height of the guide from the workpiece is adjusted to H2, and the total machining depth value HL is set to be greater than the micro-hole depth H. ; Step 4: The electrode wire feeding device drives the electrode to feed downward to process the reverse taper micro-hole. During the processing, the micro-hole processing depth H(t) is monitored in real time, and fed back to the electrical control device to change the two longitudinal ultrasonic vibrations. The amplitude Ax(t) and amplitude Ay(t) of the energy generator are adjusted in real time according to the equation shown in formula (4), so that the length of the semi-major axis of the micro-hole section at the processing depth H(t) is x(t), and the micro-hole cross-section length is x(t). The length of the short semi-axis of the hole section is y(t); Step 5. When the machining depth H(t) reaches the total machining depth, the machining of the reverse taper micro-hole is completed, the length of the long semi-axis at the entrance of the reverse taper is Dx1, the length of the short semi-axis at the entrance of the micro-hole is Dy1, and the length of the long semi-axis at the exit of the micro-hole is Dx1. Dx2, the short semi-axis length of the micro-hole outlet Dy2; Step 6: The dual excitation ultrasonic vibration transducer stops working, and the electrode wire feeding device drives the electrode back to the processing origin, waiting for the next micro-hole processing.

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